In the fifth column, you ask why we don't turn to renewables 'when we have such abundant sun, wind and hydro resources? Answers: sun because it's very expensive and the technology will take many decades to work up to the massive scale required; wind because it's expensive and intermittent (see below) and, unlike Denmark, we have no powerful neighbours to support us when the wind drops; hydro because we have little locally and Inga, on which work has now sadly stopped, is 3000km away over politically unstable territory. I have no doubt that you believe all these things are feasible and must therefore be astonished that Eskom does not rush out and implement them. You are therefore obliged to attribute this failure to stupidity on the part of Eskom and malign influence on the part of the mining and, presumably, nuclear industries. Maybe it's not. Just maybe, the decisions are rational - if pedestrian.
You then say that we could generate base-load power from CSP and 'thermal batteries'. I can only imagine that a thermal battery is a tank full of molten salt. According to the Eskom guru on the subject, you need 50 000 tons of molten sodium/potassium nitrate working between 300 and 600 deg C for each 100 MWe tower. A technology in its infancy. I don't know of one working anywhere. Again, it is surely misleading not to mention the considerable cost involved. And has anyone in the environmental camp looked at the environmental and energy costs of procuring all the structural and other materials needed? It would, for example, need 900 000 tons of molten salt to replace Koeberg.
Just as a matter of interest, it would need a single mirror 24 km in diameter to generate the 240 000 GWh/year of electricity we use. Or, since I know you prefer the concept of distributed generation operated by the local population, rather more than a thousand 100 MWe towers, each with its 50 000 tons of molten salt, located in the sunnier parts of the country.
Finally, as you will recall, I keep harping on about the need to master the arithmetic of energy generation.
Take wind. Again, according to the same Eskom guru, from a wind farm, you get full power for about 5% of the time, nothing for about 35% when the wind is either too strong of too gentle, and a variable, intermediate power level for about 60%. Overall, in this country, you do well to achieve 20%. I understand that Klipheuwel almost gets there.
A 100 MWe wind farm will therefore give you on average 20MW, or 20 x 8760 MWh per year = 20 x 8,760 GWh/y = 175,2 GWh/y.
Now, as a nation we use 240 000 GWh/y. We would therefore need 240 000 / 175,2 x 100 MW of wind power, i.e. 136 986 MW, i.e. about 68 500 x 2MW windmills.
Now, you must place these windmills about five diameters apart, say 400m. So you would need a line of windmills 27 000 km long. Assuming that we have a 'smoothed-out' coastline 4000km long, you would need at least six lines of 2 MW windmills (twice as big as those at
Klipheuwel) stretching from Namibia to Mozambique. Why do wind enthusiasts not tell us things like that?
Of course, if we could miraculously call those lines of windmills into existence, we would have far too much energy on one day, far too little the next. We would therefore also have to call into existence perhaps 20 000 MW of coal or nuclear power to cover for bad wind days. And if we have to build those more dependable stations anyway, why build the windmills in the first place? South Africa has no external back-up or significant pumped storage. You have to accept, therefore, that wind can play only a minor (and expensive) part in our planning. I'm not convinced that we can justify any at all, other than for R&D.
Again, Koeberg generates about 1800 x 8760 x 0,9 MWh/y = 14, 2 million MWh/y = 14 200 GWh/y. So we would need 14 200/175,2 x 100 MW of windmills to replace it = 8105 MW of windmills. If we use big 5 MW off-shore machines as high as the Statue of Liberty, we would need only 1620.
Now then, the spacing required would be about 1km in the SE-NW direction and 500m across wind, i.e. two windmills per km2. We would therefore need about 810 km2, i.e. an area of ocean some 28 km square. This is about the area of False Bay totally covered with the largest windmills.
How's that for environmental impact? Is that really preferable to Koeberg? Think also of the building and decommissioning perhaps twenty years later. And then the rebuilding. Good-bye whales!
We all clearly have inbuilt filters. We internalise only 'facts' that resonate with what we already believe. And we believe only what our personalities incline us to believe. We accept uncritically 'facts', however bizarre, that suit our cause and reiterate, even embellish, those facts as time goes by.
The simple facts are that we must economise. Our lifestyles will have to contract. Electricity and oil costs will see to that. For the good of the planet we must develop renewables to the fullest extent that technical and, particularly, economic factors allow. For the same reason we must go nuclear as fast as the sadly depleted global nuclear industry can manage. The energy in the nucleus is surely as much a gift of God as is the sun. What folly, in the grim on-coming energy situation, not to develop it! Our children will not thank us if we burn up all their fossil reserves, despoil their environment and fail to bequeath to them viable generation technologies, renewable and otherwise.
but its the only way I see something like solar being viable, instead of taking up half of the karoo to generate the same amount of power
Sign up with Google